Electroless nickel plating is a process used to deposit one or more layers of nickel onto a substrate without the use of an outside power source. Electroless nickel is also referred to as “autocatalytic” plating because the metal being applied is in solution and adheres itself to the substrate with the use of an electrical power current. Thus, one of the primary benefits of electroless deposition is that it requires no electricity for metallic deposition. Electroless plating also differs from “immersion” plating in that desired thicknesses of the deposited layer(s) can be achieved in contrast to immersion plating in which coverage with only nominal thickness may be achieved.
Electroless nickel processes are capable of depositing a reliable, repeatable nickel coating of uniform thickness on various substrates, including non-conductive or dielectric substrates such as plastics and ceramics and on metal substrates, including steel, aluminum, brass, copper and zinc. Because electroless nickel is free from flux-density and power supply issues, it is capable of providing an even deposit regardless of workpiece geometry. Thus, it is capable of effectively coating substrates with complex geometries, including sharp edges, deep recesses, internal areas, seams and threads, without resulting in excessive build up on points, corners, etc. In addition, electroless nickel coatings also demonstrate excellent corrosion protection and improved wear resistance as well as good lubricity, high hardness and good ductility.
Electroless nickel may be used for the coating of non-conductive substrates such as plastic substrates, to render the surface of such substrates conductive and/or to change the appearance of the substrate. Furthermore, by the deposition of nickel, the material properties of the coated substrate can be improved, including corrosion resistance, hardness and wear resistance.
However, while various electroless nickel plating compositions are known in the art, there remains a need in the art for electroless nickel plating compositions and processes that are capable of producing bright nickel deposits on various substrates.